Development of Long-acting Firdapse on Track, Catalyst Says

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by Diana Campelo Delgado |

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Editor’s note: This story was updated March 31, 2021, to clarify that Firdapse is currently the only therapy approved in the U.S. to treat adults with LEMS. Ruzurgi also is approved in the U.S. to treat children and adolescents, ages 6–16, with LEMS.

Development of a new long-acting formulation of Firdapse (amifampridine) remains on track, according to Catalyst Pharmaceuticals, the therapy’s developer.

In a year-end update, the company announced the completion of the first pharmacokinetic study testing three of Firdapse’s most promising candidate formulations. Pharmacokinetic studies are those that investigate the movement of a compound into, through, and out of the body.

At the time, Catalyst also stated it was working closely with physicians and patients with Lambert-Eaton myasthenic syndrome (LEMS) to determine the most desirable characteristics of the therapy’s long-acting formulation for that patient community.

Now the company announced the development program for Firdapse’s long-acting formulation remains on track, with additional pharmacokinetic studies that will build on data from the first study completed last year, expected to launch this year.

“We are extremely pleased with our continued commercial execution of the Firdapse launch during 2020,” Patrick J. McEnany, chairman and CEO of Catalyst, said in a press release.

Firdapse is the first and only oral therapy approved in the U.S. for adults, ages 17 and older, with LEMS, an autoimmune disease characterized by muscle weakness that usually starts in the legs. It also is approved for the same indication in the EU, Canada, and elsewhere. Ruzurgi (amifampridine) also is approved in the U.S. to treat children and adolescents, ages 6–16, with the disease.

Licensing rights for its development and commercialization in North America have belonged to Catalyst since October 2012. Last year, the company also secured a patent, which will expire in 2034, covering and protecting the intellectual rights of specific dosing regimens for patients who break down amifampridine, Firdapse’s active ingredient, at a slower pace.

In its most recent financial update, Catalyst also stated that LEMS patients on Firdapse continue to be “fairly stable and very compliant” to the regimen. The company assured there were no disruptions in the therapy’s supply chain or production, and that its current stock is suitable for anticipated needs.

By achieving record revenues for Firdapse last year in treating adults with LEMS, Catalyst stated it is in a favorable position to expand the therapy’s commercialization in the U.S., as well as to develop ongoing programs evaluating Firdapse as a potential treatment for other neuromuscular conditions.

“Despite the challenges of dealing with COVID-19, we were able grow our revenues 16% during 2020 over 2019 … We believe that we are well positioned to accelerate our rate of growth with new patient starts and revenue as the year progresses,” McEnany said.

This year, Catalyst also is planning to launch a proof-of-concept study that will evaluate Firdapse as a potential treatment for hereditary neuropathy with liability to pressure palsies (HNPP), an inherited disease that causes nerve damage. The trial is expected to begin in the second half of the year.

Moreover, the company is planning to meet with the U.S. Food and Drug Administration in the first half of the year to discuss revisions to the design and protocol of a study aiming to explore Firdapse’s therapeutic potential for the treatment of MuSK antibody-positive myasthenia gravis, another neuromuscular disorder.

“Our strong balance sheet, earnings power and borrowing capability has us well-positioned to execute on our strategic initiative to expand our product and pipeline portfolio of therapies to treat other rare diseases,” added McEnany.